STUDIO ACOUSTICS
High frequencies are best absorbed by porous, fibrous materials such as fiberglass insulation, acoustic tile, foam plastic, carpeting, and curtains. Spacing these materials several inches from the wall extends their absorbtion into the midbass region. Low frequency absorbers called bass traps can be formed of flexible surfaces such as wood panelling or linoleum mounted over a sealed air space of several inches. Cavities such as closets or air spaces behind couches are also effective sound absorbers.
If a room is absorbent at high frequencies both the live and recorded
sound are likely to be boomy and muddy, due to the persistance of low
frequency reverberation, ie. If the room has an abundance of fibrous
materials but has no bass traps. A completely dead room though is
stifling and musicians may feel they are playing in a vacuum so some
reflections are beneficial, not only for comfort but for a sense of
air and liveliness. Reflections also enhance the apparent
loudness, transient response and timbre of acoustic instruments.
-
The following acoustic treatments reduce reverberation:
Open closet doors and place couches and books a few inches from the walls.
Carpet the floor.(Not the walls)
Hang canvas from the ceiling in deep folds.
Hang thick curtains or blankets at least 2 feet from the walls, if possible.
Attach open cell acoustic foam wedges (such as Sonex or Cutting Wedge) on or near the walls. The thicker the foam the better the low
absorbtion. 4 inch foam on the walls absorbs from about 400 Hz up.
In a basement studio, nail acoustic tile to the ceiling with fibreglass insulation in the air space between tiles and ceiling.
For bass trapping make panel absorbers by nailing 1/4" and 1/8" ply to 2" furring strips (battens) and place fiberglass insulation in the air
space behind the panel. Cover about half the wall.
For wide range absorbtion attach 2" or 4" pressed fiberglass board (Owens-Corning Type 703, 3lb/cu.ft) onto 2" by 6" studs, spaced 4 ft
apart on the existing wall with fiberglass insulation in the air space. Placing the absorbent material in sections rather than all together promotes an even diffusion of sound in the room.
The following tips muffle noises from outside the studio: Weatherstrip doors all around. Replace hollow doors with solid. Block openings in thw room with thick plywood and caulking. Put several layers of plywood and carpet on the floor above the studio, and put insulation in the air space between the studio ceiling and the floor above. When building a new studio, reduce noise transmission through walls by using plastered concrete blocks. Nail gypsum board to 2x4" staggered studs.
Summarized Requirements
| requirement | result | Non parallel or absorbent walls | No flutter echoes. | Sufficient sound absorbent surfaces on walls, ceiling and floor. | Fairly low reverberation surfaces on walls, ceiling and time (about 0.4 second) | Flexible panels, cavities and fibrous materials, or fibrous materials spaced from walls and ceiling. | Equal reverb time at frequencies up to 4 kHz | A few hard reflective room surfaces | Early reflections to enhance the sound of acoustic instruments | A large or non square room and bass traps. | Minimized room modes. | A large sound absorbent room. | Low leakage. |
back to top